CN110867392A - Wafer defect scanning method - Google Patents
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- CN110867392A CN110867392A CN201911137379.XA CN201911137379A CN110867392A CN 110867392 A CN110867392 A CN 110867392A CN 201911137379 A CN201911137379 A CN 201911137379A CN 110867392 A CN110867392 A CN 110867392A
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- H01—ELECTRIC ELEMENTS
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- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
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Abstract
The invention provides a wafer defect scanning method, which comprises the following steps: acquiring an optical image of a wafer, and obtaining a pixel grid according to the optical image; acquiring all gray-scale values of the pixel grid, and determining a maximum gray-scale value and a minimum gray-scale value; defining a first region in the exposure region according to a maximum gray scale value and a second region in the exposure region according to a minimum gray scale value; performing light source training on the first area and the second area to determine an optimal light source suitable for the whole exposure area; and scanning the wafer for defects by using the optimal light source. The first area is selected by utilizing the maximum gray scale value and the second area is selected by utilizing the minimum gray scale value, so that the error of manually selecting the first area and the second area is avoided, the accuracy of configuring the light source suitable for the whole exposure area is improved, the observation of the defects of the wafer is facilitated, and the defects on the surface of the wafer can be detected in time.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to a wafer defect scanning method.
Background
As semiconductor technology is further developed, wafer defect scanning has become an indispensable tool for improving semiconductor yield, so the establishment of defect scanning process is very important.
The wafer defect scanning is completed by using a defect scanning machine, and the establishment of the scanning process program in the defect scanning machine is usually performed manually at present, wherein the light source training (light source configuration) plays a crucial role in the defect scanning process program. At present, a wafer defect scanning method usually includes manually judging and selecting a brightest area and a darkest area of a wafer surface, and performing light source training for the brightest area and the darkest area to define a proper light source intensity, so as to define a light source intensity suitable for the whole wafer surface to obtain an optimal light source for wafer defect scanning, but the wafer defect scanning method has many human factors, for example, when the brightest area and the darkest area of the wafer surface are determined, if the human judgment or selection is wrong, the defined light source is easy to be poor, so that an optical image of the wafer surface under the poor light source is too bright or too dark, which is not beneficial to observing the wafer defects, and many defects on the wafer surface cannot be detected in time, which causes yield loss of a semiconductor device; in addition, the wafer defect scanning method also consumes higher labor cost, occupies a large amount of production time of the machine, and affects the productivity of the machine.
Disclosure of Invention
The invention aims to provide a wafer defect scanning method to solve the problem that the wafer defect cannot be detected in time due to the fact that a scanning light source is not appropriate.
To solve the above technical problem, the present invention provides a method for scanning a wafer defect, comprising:
acquiring an optical image of an exposure area on the surface of a wafer, and obtaining a pixel grid according to the optical image;
acquiring all gray-scale values shown by the pixel grids, and determining a maximum gray-scale value and a minimum gray-scale value;
defining a first region in the exposure region according to a maximum gray scale value and a second region in the exposure region according to a minimum gray scale value;
performing light source training on the first area and the second area to determine an optimal light source suitable for the whole exposure area;
and scanning the wafer for defects by using the optimal light source.
Optionally, in the wafer defect scanning method, an image processing algorithm is used to obtain a pixel grid according to the optical image, and all gray-scale values represented by the pixel grid are obtained.
Optionally, in the wafer defect scanning method, the pixel grid is obtained by performing digital-to-analog conversion on the optical image.
Optionally, in the wafer defect scanning method, the gray scale value is 0 to 255.
Optionally, in the wafer defect scanning method, the center of the first area is the exposure area corresponding to the maximum gray scale value; the center of the second area is the exposure area corresponding to the minimum gray scale value.
Optionally, in the wafer defect scanning method, when the light source training is performed on the first area and the second area, the optimal light source covers the entire exposure area.
Optionally, in the wafer defect scanning method, according to different gray scale values, different light source intensities are configured for the exposure area by the optimal light source.
Optionally, in the wafer defect scanning method, all gray-scale values in the exposure area are in a normal distribution trend under different light source intensities of the optimal light source.
Optionally, in the wafer defect scanning method, a bright-field defect scanner is used to scan the wafer for defects.
Optionally, in the wafer defect scanning method, before acquiring the optical image of the wafer surface, the wafer defect scanning method further includes:
and aligning the bright field defect scanning machine with the wafer.
In summary, the present invention provides a method for scanning a wafer defect, comprising: acquiring an optical image of a wafer, and obtaining a pixel grid according to the optical image; acquiring all gray-scale values of the pixel grid, and determining a maximum gray-scale value and a minimum gray-scale value; defining a first region in the exposure region according to a maximum gray scale value and a second region in the exposure region according to a minimum gray scale value; performing light source training on the first area and the second area to determine an optimal light source suitable for the whole exposure area; and scanning the wafer for defects by using the optimal light source. The first area is selected by using the maximum gray scale value and the second area is selected by using the minimum gray scale value, so that the error of manually selecting the first area and the second area is avoided, the accuracy of configuring a light source suitable for the whole exposure area is improved, the observation of wafer defects is facilitated, the defects on the surface of a wafer can be detected in time, the yield of semiconductor devices is improved, the labor cost is reduced, the working efficiency is improved, and the productivity of a machine table is improved.
Drawings
FIG. 1 is a flowchart of a wafer defect scanning method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a pixel grid according to an embodiment of the invention;
fig. 3 is a schematic diagram of an optimal light source configuration according to an embodiment of the present invention.
Detailed Description
The wafer defect scanning method proposed by the present invention is further described in detail with reference to the accompanying drawings and the specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.
The invention provides a wafer defect scanning method, and referring to fig. 1, fig. 1 is a flowchart of a wafer defect scanning method according to an embodiment of the invention, wherein the wafer defect scanning method includes:
s10: and acquiring an optical image of an exposure area on the surface of the wafer, and obtaining a pixel grid according to the optical image. Specifically, in the embodiment, a Bright field (Bright field) defect scanner is selected to scan the wafer defects, and the Bright field defect scanner has an optical image collecting function and is provided with a light source and a sensor. Before collecting the optical image of the surface of the wafer, the method also comprises the step of aligning the bright field defect scanning machine with the wafer. And acquiring an optical image of the exposure area on the surface of the wafer by using the bright field defect scanning machine, wherein the optical image of the surface of the wafer is acquired by scanning the exposure area on the surface of the whole wafer, which needs defect scanning, so as to acquire optical images of all chip areas (DIE) on the surface of the whole wafer, which need defect scanning. Further, an image processing algorithm is added in the bright field defect scanning machine, digital-to-analog conversion is carried out on the optical image by using the image processing algorithm to obtain a pixel grid, and all gray-scale values shown by the pixel grid are obtained. And performing digital-to-analog conversion on the optical image to obtain the pixel grid.
S20: and acquiring all gray-scale values shown by the pixel grid, and determining the maximum gray-scale value and the minimum gray-scale value. Specifically, referring to fig. 2, fig. 2 is a schematic diagram of a pixel grid according to an embodiment of the present invention, where the pixel grid obtained by optical image conversion has a plurality of cells, where one cell has a corresponding gray scale value, and each gray scale value is between 0 and 255, and in principle of the gray scale value, the gray scale of the pixel grid changes from black to white in a gray scale of 0 to 255 of the gray scale value of the pixel grid.
S30: a first region is defined in the exposure region according to a maximum gray scale value, and a second region is defined in the exposure region according to a minimum gray scale value. Specifically, as shown in fig. 2, in a pixel grid corresponding to an exposure area on the surface of the wafer, a maximum gray scale value is 253, a minimum gray scale value is 1, and the first area is defined according to the maximum gray scale value, that is, a brightest area in the exposure area is defined according to the maximum gray scale value; defining the second area according to the minimum gray scale value, namely defining the darkest area in the exposure area according to the minimum gray scale value, wherein the center of the first area (the brightest area) is the exposure area corresponding to the maximum gray scale value; the center of the second area (the darkest area) is the exposure area corresponding to the minimum gray scale value. In this embodiment, the brightest area is defined as the first area, and there may be a plurality of first areas in the exposure area, that is, if the gray-scale value in the pixel grid of the first area is between 249-255 (it can be understood that the gray-scale value between 249-255 is the maximum gray-scale value), the pixel grid with the gray-scale value between 249-255 is selected and defined as the first area; defining the darkest area as the second area, wherein the exposure area can have a plurality of second areas, namely if the gray-scale value in the pixel grid of the second area is between 0 and 5 (it can be understood that the gray-scale value between 0 and 5 is the minimum gray-scale value), selecting and defining the pixel grid with the gray-scale value between 0 and 5 as the second area. The first area is selected by utilizing the maximum gray scale value and the second area is selected by utilizing the minimum gray scale value, so that the error of manually selecting the first area and the second area is avoided, the accuracy of configuring the light source suitable for the whole exposure area is improved, the observation of the defects of the wafer is facilitated, and the defects on the surface of the wafer can be detected in time.
S40: and performing light source training on the first area and the second area to determine an optimal light source suitable for the whole exposure area. Specifically, since the first region is selected using the maximum grayscale value and the second region is selected using the minimum grayscale value, the light source performing the light source training covers the brightest region and the darkest region in the entire exposure region, so that the light source performing the light source training can cover the entire exposure region. According to different gray-scale values, the optimal light source configures different light source intensities for the exposure area, referring to fig. 3, fig. 3 is a schematic diagram of an optimal light source configuration according to an embodiment of the present invention, and all gray-scale values in the exposure area are in a normal distribution trend under different light source intensities of the optimal light source.
S50: and scanning the wafer for defects by using the optimal light source. Specifically, after the bright field defect scanning machine automatically selects the optimal light source, the optimal light source is utilized to perform defect scanning on the wafer, so that a clear optical image can be obtained, workers can observe the defects of the wafer conveniently, the defects on the surface of the wafer can be detected in time, the product yield is guaranteed, the first area (the brightest area) and the second area (the darkest area) are selected according to the gray scale value, the workers do not need to judge and select the brightest area and the darkest area on the optical image by naked eyes, the labor cost is reduced, the working efficiency is improved, and the machine productivity is improved.
In summary, the present invention provides a method for scanning a wafer defect, comprising: acquiring an optical image of a wafer, and obtaining a pixel grid according to the optical image; acquiring all gray-scale values of the pixel grid, and determining a maximum gray-scale value and a minimum gray-scale value; defining a first region in the exposure region according to a maximum gray scale value and a second region in the exposure region according to a minimum gray scale value; performing light source training on the first area and the second area to determine an optimal light source suitable for the whole exposure area; and scanning the wafer for defects by using the optimal light source. The first area is selected by using the maximum gray scale value and the second area is selected by using the minimum gray scale value, so that the error of manually selecting the first area and the second area is avoided, the accuracy of configuring a light source suitable for the whole exposure area is improved, the observation of wafer defects is facilitated, the defects on the surface of a wafer can be detected in time, the yield of semiconductor devices is improved, the labor cost is reduced, the working efficiency is improved, and the productivity of a machine table is improved.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (10)
1. A method for scanning a wafer defect, comprising:
acquiring an optical image of an exposure area on the surface of a wafer, and obtaining a pixel grid according to the optical image;
acquiring all gray-scale values shown by the pixel grids, and determining a maximum gray-scale value and a minimum gray-scale value;
defining a first region in the exposure region according to a maximum gray scale value and a second region in the exposure region according to a minimum gray scale value;
performing light source training on the first area and the second area to determine an optimal light source suitable for the whole exposure area;
and scanning the wafer for defects by using the optimal light source.
2. The wafer defect scanning method as claimed in claim 1, wherein an image processing algorithm is used to obtain a pixel grid from the optical image, and all gray scale values exhibited by the pixel grid are obtained.
3. The wafer defect scanning method of claim 2, wherein the pixel grid is obtained by performing digital-to-analog conversion on the optical image.
4. The wafer defect scanning method as claimed in claim 1, wherein the gray scale value is 0-255.
5. The wafer defect scanning method as claimed in claim 1, wherein the center of the first area is the exposure area corresponding to the maximum gray-scale value; the center of the second area is the exposure area corresponding to the minimum gray scale value.
6. The wafer defect scanning method of claim 1, wherein when performing light source training for the first area and the second area, the optimal light source covers the entire exposure area.
7. The wafer defect scanning method as claimed in claim 6, wherein the optimal light source is configured with different light source intensities for the exposure area according to different gray scale values.
8. The wafer defect scanning method as claimed in claim 7, wherein all gray-scale values in the exposure area are in a normal distribution trend under different light source intensities of the optimal light source.
9. The wafer defect scanning method of claim 1, wherein the wafer is defect scanned using a bright field defect scanner stage.
10. The wafer defect scanning method of claim 9, wherein prior to acquiring the optical image of the wafer surface, the wafer defect scanning method further comprises:
and aligning the bright field defect scanning machine with the wafer.
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Cited By (3)
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| CN111879785A (en) * | 2020-07-31 | 2020-11-03 | 华虹半导体(无锡)有限公司 | Method for detecting abnormal film thickness |
| CN114937041A (en) * | 2022-07-25 | 2022-08-23 | 聊城市博源节能科技有限公司 | Method and system for detecting defects of copper bush of oil way of automobile engine |
| US11935244B2 (en) | 2020-10-29 | 2024-03-19 | Changxin Memory Technologies, Inc. | Method and apparatus for improving sensitivity of wafer detection, and storage medium |
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